Your normal PVC cement should be fine as far as I'm aware, if not then I'm sure someone will chip in. Usually a frame will be a U shape so that the rocks at the top will not topple over, e.g. the U shape is on it's side (hope that makes sense)!
You then need to drill holes in your rock and then feed them into the PVC tubing and stick into place. I think it sounds more difficult than it actually is. I have seen a few pics where there has been some fantastic rock overhangs and can be very effective. I suppose the only tricky bit is planning where all the rocks will go.

This thread is also great, get to page 2 and you will see how he constructed his rock with lots of pics too. In fact I have never seen this method before and it's pretty cool:My 220 build - Vivid Aquariums Forums

Random thought I had- there is the normal white pvc and then there is the dark gray underground rated kind. I was planning to use gray as it would be less visible, but I believe its UG conduit, and therfore not water-quality rated. Any plumbers care to chime in? Sparky maybe?

does drilling the pipe to let water in and out of the pipe seem to be a good idea?

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i would with holes about 1/4-3/8" every couple inches that way the pvc structure wont be compromised and will allow the water to not become stagnet in the pipe. also allows a place for copopods to multiply

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